ANOMALOUS KRYPTON IN THE ALLENDE METEORITE, Urs Frick, Department of Physics, University of California, Berkeley, CA 94720. Anders and coworkers at Chicago [1,2] discovered that one can enrich isotopically anomalous Kr and Xe from the Allende meteorite by "etching" HCR/HF resistant residues in oxidizing acids. We have extended this approach using atomic oxygen (0') and hydrogen peroxide (H202). In an accompanying abstract we describe our analyses of He,Ne,Ar,Kr, and Xe in a series of samples from Allende [3]. Measurements on samples obtained by various meth- ods confirm the Xe data of the Chicago group [1,2]: isotopic correlations for Xe from both laboratories agree within errors and exhibit a similar "range of anomaly." The most striking feature is the close correlation for the lightest and heaviest Xe isotopes; both are sometimes enriched relative to l3 OX^ by a factor of 2. In this paper we report for the first time reli- able data for the lightest Kr isotopes (Fig. 1). We summarize our results: (a) Both Kr and Xe data are consistent with a two component mixture of "ordinary" and "anomalous" planetary gases. The presence of a possible third component with the isotopic composition of solar Kr and Xe would be completely obscured for ordinary levels of concentration by the huge planetary abundances. From the Xe data it is obvious that these gas rich residues do not contain significant amounts of atmospheric gases. Conventional spallation on chondritic material contributes to Kr and Xe iso- topes in the samples in a minor way at best. (b) The Xe isotopic correlations 6(M/132) versus 6(136/132) are almost identical with least square fitted lines through data from stepwise heating of a "carbon" sample from the Orgueil meteorite 141, but they are dissimilar to the lines observed when bulk samples of Allende or Mokoia were subjected to stepwise degassing [6]. The Kr iso- topic correlation lines can be expressed as follows: 6 (M/82) = A + B 6 (86182) (see Table). M A (Allende) A (Orgueil) (Allende) (Orgueil) 84 -2222 permil -8+3 permil .527+27 .635+41 83 - 4*4 -5+1 .458+32 .450+32 80 17+3 -8t3 -.115+16 .115*50 78 17510 25+38 -.787+100 .182+650 Where the pattern for the two meteorites are discordant, those for Orgueil are not very well established. The Kr data from Allende are plotted in Fig. 1. (c) While the light Xe isotopes are enriched in correlation with the heavy ones, the light Kr isotopes (78,80) anticorrelate with the heavy ones (83,84,86). The two patterns are contrasted in Fig. 2 for a highly anomalous sample (colloidal "carbon" after treatment with atomic oxygen). We have failed to find a simple explanation for the result. An experi- mental artifact can almost certainly be ruled out. Spallation effects [5] cannot account for decreased ratios of 78/82 or 80182. Thermal neutrons on bromine (7 9~r[n,~@] OKr and "Br [n,~B] 82~r)should increase the 80182 ratio, contrary to what is seen. 0 Lunar and Planetary Institute Provided by the NASA Astrophysics Data System ANOMALOUS KRYPTON IN ALLENDE Urs Frick Fractionation processes should influence Kr and Xe isotopes in a similar manner. The "positive" Xe and the "negative" Kr anomaly for the light iso- topes certainly does not favor the possibility of mass fractionation, which has been suggested [I] to explain the excess of light Xe isotopes. A possible explanation would be nucleosynthetic inhomogeneities that were somehow pre- served in the early solar system as by "presolar" grains, loaded with heavy noble gases of anomalous isotopic composition, mixing incompletely with the remainder of the material in the planetary nebula. An attempt to identify the carrier material and to characterize the trapping processes for noble gases in such a material is discussed briefly in an accompanying abstract [3]. The farther we proceed in these studies the less we are inclinedto accept in situ fission of a superheavy element as the origin of the anomalies in the heavy isotopes of Xe [I]. This work has been supported by NASA and ERDA. References : 1. R,S. Lewis, B. Srinivasan and E. Anders (1975) Science, Vol. 190, 1252-1262. 2. R.S. Lewis, J. Gros, and E. Anders (1976) preprint submitted to Journ. Geophys. Res. 3. U. rick and J.H. Reynolds (1977) in this volume. 4. U. Frick and R.K. Moniot (1976) Meteoritics, in press. 5. K. Marti, P. Eberhardt, and J. Geiss (1966) Z. Naturforsch. 21a, 398-413. 6. D.L. Phinney (1971) Ph.D. thesis, University of Minnesota, Minneapolis. 0 Lunar and Planetary Institute Provided by the NASA Astrophysics Data System ANOMALOUS KRYPTON IN ALLENDE Urs Frick UC BERKELEY , , 1 , , ;+I MSL 7702 0 100 20 300 400 0 100 axl 300 Lm 6 [El 6IEl Fig. 1. Isotopic correlation diagram for Krypton in HCR/HF resistant residues from the Allende carbonaceous chondrite. The 6 - values are normalized to atmospheric Kr. 0- - 4 "SOLAR" UC BER- MSL 7703 Fig. 2. Krypton and Xenon isotopes in an anomalous sample: "ash" of a carbon-rich colloid after treatment in atomic oxygen. 6 - values are normalized to atmos- pheric isotopic composition. 0 Lunar and Planetary Institute Provided by the NASA Astrophysics Data System .